Page 149 -

138 M. Adams
“normal” specification of the host enactment engine, this method would already
be available within the engine.
Launch case: The service must have the ability to launch an instance of a loaded
worklet specification.
Cancel case: The service requires the means to cancel a launched worklet
instance (e.g., if the work item it has substituted for is canceled, then the worklet
instance would typically need to also be canceled).
Check-out work item: When the service has been notified of an enabled work
item, and there is a worklet to act as a substitute for it, the service needs a way to
take control of the work item’s execution. Thus, by “checking out” the work item
from the engine, the engine would pass responsibility for the execution of the
work item to the service, and wait for the service to notify it that the execution
has completed (i.e., when the worklet case completes).
Check-in work item: When a worklet instance has completed, the service will
notify the engine that execution of the original work item it acted as a substitute
for has completed. The data gathered by the worklet would be mapped to the
work item before it was checked in.

Figure 4.4 summarizes the interface required by the service’s selection process.

Fig. 4.4 Required selection interface